Method and means for repeating



Patentl Sept. 9, 1924.

UNITED STATES PATENT loFFlcE.

mammina 1L NrcoLeoN, or IEW Your. Y., Assuan-onl 'ro wnsmir me comun, mconronam, or imw Yoann. Y., A. CORPORATION or maroni.

l n'rnon aim means ron. nnmrnm.

' appunti and umn 1s, 191s. serial No. 223,222.

To all whom it may concern:

Beit known that I, AmexANDER M. NICOL- soN, a subject of the King of VGreat Britain, residin at New York, in the county of New York, tate of NewYork, have invented certain new and useful. Improvements in Methods and Means for Repeating, of which the following is a full, clear, conclse, and exact description.

' This invention relates to method and means for repeating in which weak impulses received at a repeating. station are to be repeated and sent 'outupon the line in amplied form. Such a .repeating means may be inserted in a telephone line, for instance, and in this'case ,it is necessary that the repeater transmit currents in both directions` over -the line to provide for transmission of signals. l

It is an object of the present invention to provide for .such two-way repeating. d

A repeating element such as a vacuum tube repeater is inherently a unilateral lconductor and in order to provide-for bilateral repeating, it has been proposed to use-either (a) the two-way two repeaters connected in opposition between the line sectionsor (b) asingle repeater which is reversibly connected between the line sections. lTli'e'irst expedient is open to objection because the input of one repeater being connected to the output of the other, causes a useless and, in fact, objectionable .circulation of power at the repeating station to take place, resultin in some instances in 'n or howling ue to the generation of'auib efrequency currents. This'objection has been reviously overcome by various schemes whic depend for their operation u on simulating or modifying the impedance ci, the telephone line. The scheme under (b) is objectionable because of the use of switch contacts which must be opened and closed.

The present inventionv aims to provide for two-way repeating without involving the necessity of simulating or modifying the line im ance or of reversing the pointing of a umlateral repeating element, or. of using switching means to prevent transmission'l thro'ngha repeating path.

- To this end useis made of two vacuum tube 're aters' connected in opposition be tween t e'two line sections andof the fact that such repeaters may be rendered inopetative by. temporarily assi 'ng a. sufeiently high negative potential to the control electrode of the repeater. This -serves to l reduce the space current within the vacuum Atube substantially to zero. A. positive potential on the control electrode, however, permits the vacuum tube to remain operative.

Another object of the invention is to automaticall'yxeduce the transmission efficiency4 l of the repeating paths independently ofthe current to be repeated.

In accordance with the inventiona generator of alternating current is oppositely connectedto the two repeaters so that .the repeaters are alternately rendered inoperative at a frequency which is the frequency delivered by the generator. One fre ater -is thus rendered inoperative when t e other is operative, soA that a local circulation of power is prevented. Either repeater, however, is always in condition to repeat the incoming impulses, due to the fact that the repeater is rendered inoperativeat afreqneny which isabove audibility, and to this end the generator delivers a frequency of the order of 25,000 cycles', although it may be more or less than this value.

Further objects and advanta vention will be a parent from t e following 'of the indetailed description of the invention taken in connection with the drawings, in which- Fig. 1 shows a two-way re ating system in which the currents 'supplie b the; nerator are applied to van auxiliary e e'ctr e within the vacuum tube repeater; and Fig.'2 is a modification of Fig. 1, in that the generator delivers its potential to the usual' input elecpotential of the 4control electrode 10 of peater 5 'with respect to its filament 7,there.g y the 'space current in the out ut''v side' of this re ter then variations transmitted 'ough large condenser 11 and transmitted to the line 9. When generator 9y supplica the comparatively 4 a wave which makes the auxiliary electrode 6 negative with respect to the ilament 7, the space current within the `repeater 5 is reduced substantially yto zero and this repeater is thereby rendered inoperative. When the generatori) supplies a wave which makes the auxiliary electrode 6 positive with respect to the filament 7 the repeater 5 is in condition to repeat current from the line 1 to the line 2. The frequency supplied by the generator 9 "will, be of the order of 25,000 cycles. The times when the repeater 5 is inoperative do not interfere with this repeater being always in a condition to transmit current from the line 1 to the line 2.

The repeater path 4 is similar to the repeater path 3, except that'the generator 9 is o positely connected to these two repeater pat s, whereby one repeater is permitted to remain operative while the other one is rendered inoperative.l This insures that a local circulation of power between the repeaters will be prevented. If it is desired to prevent the high frequency delivered by the generator 9 from being sent out upon the line, the condenser 12 in shunt t-o the output Side of the repeater 5 and a similar condenser 13 for the other repeater may be provided. These condensers have a comparatively small capacity and while preventing the passage of currents of relatively low frequencies which are to be repeated, these condensers permit the passage of currents of the frequency delivered by the generator 9 and thereby revent such current from being transmitte to either of the lines 1 or 2.

The arrangement in Fi 2 is substantially the'same as that above escribed, the only difference bein that the generator 9 by means of the coils 14 and 15 delivers its potential directly between the usual cathode and control electrode of the repeater.

Although the invention has been set forth with especial reference to its application to the repeating of voice frequency currents it is of course also a plicable to the repeating of currents of other frequencies, whether higher or lower. It is understood that the invention is not limited to the particular circuit arrangements set forth herein, but is capable, of embodiment in many and widely varied arrangements within the scope of the appended claims.

-What is claimed is:

'1. A two-way repeating :system comprising two lines, two repeater paths connected in opposition therebetween, and means supplying electromotive forces for rendering said repeater paths substantially inoperative in cyclic order.

2. A two-.way repeating system comprising two lines, two repeater paths connectedA in opposition therebetween, and suptially Lacasse plying electromotive forces for rendering said repeater paths substantially inoperative in cyclic order at a frequency which does not interfere with the transmission of signals.

3. A two-way repeating Ysystem comprising two lines, two repeater paths connected in opposition therebetween, each of said paths comprising a 4vacuum tube repeater, and means acting electrically upon the discharge paths of said tubes for rendering said tubes substantially inoperative in cyclic order.

4. A repeating system comprising a line, repeating means therefor adapted to repeat waves in substantially the same form as received, and means supplying electromotive forces for periodically rendering said repeating means inoperative while repeating.

5. A repeating system comprising a line, two-way repeating means, energizin means adapted to supply direct current t erefor, and means for reducing the current from said energizing means substantially to zero while leaving said energizing means connected in circuit, for preventing a local circulation of power through said repeating means.

6. The method of operating a repeater energized by1 direct current which comprises repeating in opposite directions .with said repeater and preventing a local circulation of the power at the repeater by reducing the energizing direct current therefor to a small value at such times as permits the normal repeating operation and while leaving the energizing circuit connected to the repeater.

7 A two-way repeating system comprising two lines, two vacuum tube repeaters pointing in opposite directions between said lines, means for supplying space current for said tubes, and means for reducing substanto zero the' space current within said tubes.

' 8. A two-way repeating system comprising two lines, two vacuum tube repeaters pointing in opposite directions between said lines, means for supplying space current for said tubes, and means for cyclically reducing substantially tozero the space current within said tubes.

9. A two-way repeating system comprising two lines, two vacuum tube repeater paths pointing in opposite directions thereetween, and means for su plying a negative potential to an electro e within one or thev other of said tubes.

10. A two-way repeating systemcomprising two lines, two vacuum tube repeater paths pointing in opposite directions thereetween, and means for va ing the efciency of one of said paths wit respect to the other, said means comprising a generator coupled to said paths.

11. In a repeating system, the-combination of two vacuum tube repeater paths the output side of each of which is coupled to the input side of the other, and means for increasing the ecienc of one of said paths with respect to the ot er, said means comprising a source of current in common to said paths.

12. In a repeating system, the combination of two vacuum tube re ater aths the output side of each of which 1s coup ed to the input side of the other, and a generator of alternating current oppositely connected to said paths.

13. A repeater system comprising -a line, an amplifier for handling the transmission of current in one-direction through said line, another amplifier for handling the transmission of current in the other direction through said line, means suppling electromotive forces for cyclically c anging the eciency of said amplifiers .at a rapid'rate, whereby the transmlssion of relatively low vfrequency current is possible, said means operating-to render one of said amplifiers substantlally ino rative when the other is operative, where y a local circulation of current through said amplifiers is prevented.

14. The combination of two lines, two repeuter paths opositely and permanently connected there tween, and means comprising4 a source o f electromotive force acting on oneof said paths for reducing the transmission eicienc of said path at intervals occurring' at a requency of a higher order of ma transmltted.

15. A two-way repeating system comprising two lines, two repeater aths opposltely and permanently connected connections for sup lying encrgizin current to said paths aus means indepen ent of the current to be repeated for automatically reducing to. a small value the current for one of sai'd paths when the other path is operative.

16. A two-way repeating system. comprising two lines, two vacuum tuberepeater 4paths oppositely connected therebetween, and means for automatically supplying a neggtive potential toan electrode within a tu therebetween,

gnitude than the frequency to be in each of said paths for rendering one of said paths inoperative when the other is operative.

In witness whereof, I hereunto subscribe my name 1918. v

ALEXANDER M.. NICOLSON.

this `12th day of March, A. D. Y 

